Recently, concerns about depletion of fossil fuel resources and environmental pollution are increasing globally and the energy problem is becoming an important social issue due to change in oil prices, effectuation of the UN Framework Convention on Climate Change, etc. In particular, with the prediction of depletion of petroleum which is used in all industrial fields, the energy problem is becoming an important threat to national security and survival. For this reason, interests in biofuels that can replace the fossil fuel are increasing consistently.
A biofuel refers to a fuel obtained from biomass, including not only living organisms but also byproducts of metabolic activities such as excrement of animals. It is a renewable source of energy, unlike the fossil fuel. Recently, also in Korea, development of biofuels using microorganisms is being studied actively with the advance in biotechnology and attempts are made to extend its scope to bioethanol, biobutanol, biodiesel, etc.